High performance integrated circuit (IC) packages are well known in the art. Improvements in IC packages are driven by industry demands for increased thermal and electrical performance and decreased size and cost of manufacture.
In general, array packaging such as Tape Ball Grid Array (TBGA) packages provide a high density of interconnects relative to the surface area of the package. Typical TBGA packages include a flexible circuit tape substrate and a semiconductor die attached to the substrate by a die adhesive. Gold wire bonds electrically connect the die to circuitry of the substrate and the wire bonds and die are encapsulated in a molding material. Solder balls are disposed on the bottom surface of the substrate for signal transfer.
Typically, array packaging, such as ball grid array (BGA) packages provide for a high density package including a convoluted signal path, giving rise to high impedance and an inefficient thermal path which results in poor thermal dissipation performance. With increasing package density, the spreading of heat generated by the device is increasingly important.
FIG. 1 shows a sectional side view of a cavity-down BGA package indicated generally by the numeral 20. The cavity-down BGA package 20 includes a flexible circuit tape 22 of laminated layers including a signal, trace and pad layer, referred to as a conductor layer, laminated on a polyimide tape. An aperture extends through the flexible circuit tape 22 and the flexible circuit tape 22 is laminated to a heat spreader 24 which includes a cavity that is aligned with the cavity of the flexible circuit tape 22. A semiconductor die 26 is mounted in a die-down configuration in the cavity of the heat spreader 24 and wire bonds 28 extend between the semiconductor die and wire-bonding sites of the flexible circuit tape 22. The semiconductor die 26 and the wire bonds 28 are encapsulated in an encapsulating material 30 which fills the cavities of the heat spreader 24 and the flexible circuit tape 22 and protrudes to cover the wire bonds 28. A number of solder balls 32 are attached to solder ball pads of the flexible circuit tape 22, in the form of a ball grid array. The heat spreader 24 provides improved heat dissipation in comparison with prior ball grid array packages.
Further improvements in thermal and electrical performance are still desirable in order to meet industry demands.